You can provide as much security as possible, but unless you strike the terrorist den, it will never be enough!
An active diplomatic approach is needed to fight against the sponsers of these terrorists as well. But first things first, clean up that mess in SW!
And where is that supposed terrorist den situated?
There is no protection against a suicide attack. It doesn't matter how many check posts or security personnels we bring for securing high profile targets. On the contrary, beefing up security (in terms of manpower) will only increase human losses should a suicide attacker blows himself there.
We can base our security plans on M15's models.